Add warning_gettext() wrapper function that changes to the user locale,

then calls gettext().
Add U_ macro that calls warning_gettext() instead of gettext().
Rename warning2()/error2() back to warning_nodebug()/error_nodebug().

plugins/sudoers/prompt.c

@@ -168,5 +168,5 @@ expand_prompt(const char *old_prompt, const char *user, const char *host)
 
 oflow:
     /* We pre-allocate enough space, so this should never happen. */
-    fatalx(_("internal error, %s overflow"), "expand_prompt()");
+    fatalx(U_("internal error, %s overflow"), "expand_prompt()");
 }